Method and system for electrical power generation

Abstract

Electrical power generation systems typically comprise an electrical power distribution arrangement in which a number of electrical power generators are coupled in parallel. In such circumstances in order to avoid conflict generally a first electrical power generator is controlled with a voltage controller while second electrical power generators have electrical current controllers. As loads are switched into and out of the electrical distribution system in normal operation the first electrical power generator and its voltage controller can accommodate voltage dynamics and therefore maintain a desired voltage. However, in order to accommodate heavier loads switching, the dynamic operation of the electrical current controller is achieved through utilizing operational voltage margins from a desired voltage as control signals to the electrical current controller. A threshold is provided above which the electrical voltage margin must operate and regimes are provided to determine continued increase or fall in the operational voltage to allow continued dynamic control of the electrical current in order that voltage stability can be re-established with regard to electrical power distribution arrangements.

1. A method of operating an electrical generator system comprising a first electrical generator, a voltage controller, a second electrical generator, a current controller and a common electrical power distribution arrangement, the first electrical generator and the second electrical generator being coupled to the common electrical power distribution arrangement, the method comprising:
 a) determining an operational voltage value for the common electrical power distribution arrangement; 
 b) comparing the operational voltage value with a desired voltage value to determine an operational voltage margin; 
 c) using the voltage controller to configure the first electrical generator to provide and substantially maintain the desired voltage value within the common electrical power distribution arrangement; and, 
 d) comparing the operational voltage margin with a predetermined voltage margin whereby if the operational voltage margin exceeds the predetermined voltage margin then the current controller for the second electrical generator providing additional electrical current to the common electrical power distribution arrangement. 
 
     
     
       2. A method as claimed in  claim 1  wherein the predetermined voltage margin is adjustable. 
     
     
       3. A method as claimed in  claim 1  wherein there are a plurality of predetermined voltage margins to alter the additional electrical current provided by the second generator. 
     
     
       4. A method as claimed in  claim 1  wherein additional electrical current is gradually altered until the operational voltage substantially equals the desired voltage. 
     
     
       5. A method as claimed in  claim 1  wherein there are a plurality of second electrical generators principally controlled by a respective current controller with each current controller associated with a voltage sensor. 
     
     
       6. A method as claimed in  claim 1  wherein the method includes determining if the operational voltage margin is increasing or decreasing when greater than the pre-determined voltage margin. 
     
     
       7. An electrical generator system comprising a first electrical generator, a voltage controller, a second electrical generator, a current controller and a common electrical power distribution arrangement, the first electrical generator and the second electrical generator being coupled to the common electrical power distribution arrangement, the first electrical generator being associated with the voltage controller, a voltage sensor to determine a voltage across the common electrical power distribution arrangement and to provide an operational voltage value, a comparator to compare the operational voltage value with a desired voltage value to determine an operational voltage margin, the voltage controller configuring the first electrical generator to provide and maintain a desired voltage value within the common electrical power distribution arrangement, the second electrical generator associated with the current controller to maintain a desired electrical current value within the common electrical power distribution arrangement, a second comparator to compare the operational voltage margin with a predetermined voltage margin whereby if the second comparator determines that the operational voltage margin exceeds the predetermined voltage margin then the current controller for the second electrical generator being arranged to provide additional electrical current to the common electrical power distribution arrangement. 
     
     
       8. A system as claimed in  claim 7  wherein the predetermined voltage margin is adjustable. 
     
     
       9. A system as claimed in  claim 7  wherein there are a plurality of predetermined voltage margins to alter the additional electrical current provided by the second generator. 
     
     
       10. A system as claimed in  claim 7  wherein additional electrical current is gradually altered, either increased or decreased until the operational voltage substantially equals the desired voltage. 
     
     
       11. A system as claimed in  claim 7  wherein there are a plurality of second electrical generators principally controlled by a respective current controller with each current controller associated with the voltage sensor. 
     
     
       12. A system as claimed in  claim 7  wherein the current controller includes means to determine whether the operational voltage margin is increasing or decreasing. 
     
     
       13. A gas turbine engine incorporating an electrical generator system as claimed in  claim 7 . 
     
     
       14. An aircraft incorporating an electrical generator system as claimed in  claim 7 .